AUTHOR=Rodríguez-Meana Bruno , Santos-Nogueira Eva , Trujillo-Vázquez Sònia , Jakob Anette , Udina Esther , Fournelle Marc , Navarro Xavier 

TITLE=Assessment of focused ultrasound stimulation to induce peripheral nerve activity and potential damage in vivo

JOURNAL=Frontiers in Neurology

VOLUME=Volume 15 - 2024

YEAR=2024

URL=https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2024.1346412

DOI=10.3389/fneur.2024.1346412

ISSN=1664-2295

ABSTRACT=In this study, we have assessed focused ultrasounds stimulation (FUS) applied in vivo to the rat peripheral nerve, with two objectives: First, to test whether FUS stimulation activates peripheral nerve axons under different stimulation conditions, and second, to evaluate whether FUS stimulation inflicts damage to the healthy nerve. FUS was delivered with three ultrasound transducers (Sonic Concept H115, H107, and H102) covering the largest set of parameters examined for US stimulation of peripheral nerves so far. We used a previously documented experimental in vivo electrophysiological set up, recording muscle and nerve responses following stimulation. We were not able to obtain a reliable evoked action potential in either the nerves or the muscles, under any FUS condition applied, neither over the skin nor directly to the nerve exposed. Additional experiments performed ex vivo and in vivo on mice, confirmed this conclusion. When FUS stimulation was applied directly to the exposed sciatic nerve, the neuromuscular functional tests decreased significantly, and recovered one week later, except for the FUS at 0.25 MHz. Histologically, degenerating nerve fibers were observed, mostly localized at the periphery of the nerve. The amount of axonal degeneration was variable, with a tendency to be higher with the lower FUS frequency.